This invention relates to hair-removal methods using optical radiation.
Unwanted hair is a common dermatological and cosmetic problem, and can be caused by heredity, malignancy, or endocrinologic diseases such as hypertrichosis (i.e., excess hair) and hirsutism (i.e., androgen-influenced hair). Hair can be temporally removed using a number of techniques including wax epilation, depilatory creams, and, of course, shaving. Alternatively, hair can be permanently removed using electrolysis; this process involves insertion of a current-carrying needle into each hair follicle, and is often painful, inefficient, and time consuming.
Optical-based methods, such as the use of laser light, have also been used for hair removal. U.S. Pat. No. 4,388,924, for example, describes irradiation of individual hair follicles using a laser; in this method, heating of the hair's root section causes coagulation in local blood vessels, resulting in removal of the follicle. Related techniques, such as those described in U.S. Pat. No. 5,226,907, involve removal of the follicle by first applying a light-absorbing substance to the region of interest, and then irradiating the substance to heat and remove the follicle.